From 12c0d1804c3c046e0e7758ac92806dcb4570435c Mon Sep 17 00:00:00 2001
From: Chris Koch <chrisko@google.com>
Date: Sat, 25 Feb 2023 23:32:43 -0800
Subject: InterfaceID: tests for FromBytes, ToBytes, and Getter

Signed-off-by: Chris Koch <chrisko@google.com>
---
 dhcpv6/option_interfaceid_test.go | 64 ++++++++++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 15 deletions(-)

diff --git a/dhcpv6/option_interfaceid_test.go b/dhcpv6/option_interfaceid_test.go
index b38cadb..640c06a 100644
--- a/dhcpv6/option_interfaceid_test.go
+++ b/dhcpv6/option_interfaceid_test.go
@@ -1,30 +1,64 @@
 package dhcpv6
 
 import (
-	"bytes"
+	"errors"
+	"fmt"
+	"reflect"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
 	"github.com/stretchr/testify/require"
+	"github.com/u-root/uio/uio"
 )
 
-func TestParseOptInterfaceID(t *testing.T) {
-	expected := []byte("DSLAM01 eth2/1/01/21")
-	var opt optInterfaceID
-	if err := opt.FromBytes(expected); err != nil {
-		t.Fatal(err)
-	}
-	if url := opt.ID; !bytes.Equal(url, expected) {
-		t.Fatalf("Invalid Interface ID. Expected %v, got %v", expected, url)
+func TestInterfaceIDParseAndGetter(t *testing.T) {
+	for i, tt := range []struct {
+		buf  []byte
+		err  error
+		want []byte
+	}{
+		{
+			buf: []byte{
+				0, 18, // Interface ID
+				0, 4, // length
+				'S', 'L', 'A', 'M',
+			},
+			want: []byte("SLAM"),
+		},
+		{
+			buf: []byte{
+				0, 18,
+				0, 0,
+			},
+		},
+		{
+			buf: []byte{0, 18, 0},
+			err: uio.ErrUnreadBytes,
+		},
+	} {
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			var ro RelayOptions
+			if err := ro.FromBytes(tt.buf); !errors.Is(err, tt.err) {
+				t.Errorf("FromBytes = %v, want %v", err, tt.err)
+			}
+			if got := ro.InterfaceID(); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("InterfaceID = %v, want %v", got, tt.want)
+			}
+
+			if tt.want != nil {
+				var m RelayOptions
+				m.Add(OptInterfaceID(tt.want))
+				got := m.ToBytes()
+				if diff := cmp.Diff(tt.buf, got); diff != "" {
+					t.Errorf("ToBytes mismatch (-want, +got): %s", diff)
+				}
+			}
+		})
 	}
 }
 
 func TestOptInterfaceID(t *testing.T) {
-	want := []byte("DSLAM01 eth2/1/01/21")
-	opt := OptInterfaceID(want)
-	if got := opt.ToBytes(); !bytes.Equal(got, want) {
-		t.Fatalf("%s.ToBytes() = %v, want %v", opt, got, want)
-	}
-
+	opt := OptInterfaceID([]byte("DSLAM01 eth2/1/01/21"))
 	require.Contains(
 		t,
 		opt.String(),
-- 
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